My sound engine currently works perfectly with listener positioning and sound positioning to create the attentuation and panning effects. At least, for short sounds.

I converted an .mp3 to .wav to test out playing a song from a specific point, but suddenly OpenAL ignores that the sound and the listener are not at the same place and just plays the song at full volume right in the center.

Has anyone ever had this problem before? If so, just what is the problem?

EDIT:
If it helps, the song is stereo and the sounds are mono, all at 16 bits per sample.